README.md

Groovy Liquibase

A pluggable parser for Liquibase that allows the
creation of changelogs in a Groovy DSL, rather than hurtful XML. If this DSL
isn't reason enough to adopt Liquibase, then there is no hope for you.

News

March 1, 2015

The Liquibase Groovy DSL now supports Liquibase 3.3.2, and is built with Groovy
2.4.1.

June 15, 2014

We are proud to announce the long awaited release of version 1.0.0 of the
Liquibase Groovy parser. Version 1.0.0 uses version the latest release of
Liquibase (3.1.1), and it appears to work fine with both Gradle 1.x releases as
well as the upcoming Gradle 2.0 release.

Tim Berglund has asked me to take on the continued maintenance of this project,
so I've had to change the maven group ID to one for which I have permission to
publish on Maven Central. Going forward, this parser will be available under
the net.saliman group id. The artifact ID, groovy-liquibase-dsl,
will remain the same.

My thanks to Tim for the opportunity to help out with this great project.

Steve Saliman

IMPORTANT NOTE FOR USERS UPGRADING FROM A PRE 1.0.0 RELEASE OF THE GROOVY DSL:

Version 1.0.0 of the Groovy Liquibase DSL uses Liquibase 3, instead of Liquibase
2, and several things have been deprecated from the Groovy DSL to maintain
compatibility with Liquibase XML. A list of deprecated items can be found in the
Usage section. To upgrade to version 1.0.0, we strongly recommend the
following procedure:

Make sure all of your Liquibase managed databases are up to date by running
an update on them before upgrading the Groovy DSL.

Create a new, throw away database to test your Liquibase change sets. Run
an update on this new database with the latest version of the Groovy DSL.
This is important because of the deprecated items in the Groovy DSL, and
because there are some subtle differences in the ways the different Liquibase
versions generate SQL. For example, adding a default value to a boolean
column in MySql using defaultValue: "0" worked fine in Liquibase 2, but
in Liquibase 3, it generates SQL that doesn't work for MySql;
defaultValueNumeric: 0 needs to be used instead.

Once you are sure all of your change sets work with the latest Groovy DSL and
Liquibase 3, clear all checksums that were calculated by Liquibase 2 by using
the clearChecksums command in all databases.

Finally, run a changeLogSync on all databases to calculate new
checksums.

Usage

The DSL syntax is intended to mirror the Liquibase XML syntax directly,
such that mapping elements and attributes from the Liquibase documentation to
Groovy builder syntax will result in a valid changelog. Hence this DSL is not
documented separately from the Liquibase XML format. We will, however let you
know about the minor differences or enhancements to the XML format, and help out
with a couple of the gaping holes in Liquibase's documentation of the XML.

Deprecated Items

In the Liquibase XML, you can set a sql attribute in a sqlFile
change, but that doesn't make a lot sense, so this has been disabled in the
Groovy DSL.

The documentation mentions a referencesUniqueColumn attribute of the
addForeignKeyConstraint change, but what it doesn't tell you is that it
is ignored. In the code, Liquibase has marked this item as being deprecated,
so we've deprecated it as well, and we let you know about it.

If you were using the DSL prior to version 1.0.0, a changeSet could have an
alwaysRun property. This is inconsistent with Liquibase and has been
replaced in 1.0.0 with runAlways

Prior to 1.0.0, the DSL allowed a path attribute in an include.
This is no longer allowed. includeAll should be used instead.

Prior to 1.0.0, the DSL allowed createStoredProcedure changes. This has
been replaced with createProcedure.

Prior to 1.0.0, the DSL allowed a File object to be passed as an attribute to
loadData and loadUpdateData changes. This is no longer supported,
the path to the file should be used instead.

Prior to 1.0.0, the DSL allowed constraint attributes to be set as methods
in a constraint closure. This is inconsistent with the rest of the DSL and
has been removed.

Additions to the XML format:

The Groovy DSL supports a simplified means of passing arguments to the
executeCommand change. Instead of:

execute {
arg(value: 'somevalue')
}

You can use this the simpler form:

execute {
arg 'somevalue'
}

The sql change does not require a closure for the actual SQL. You can
just pass the string like this: sql 'select some_stuff from some_table'
If you want to use the comments element of a sql change, you need
to use the closure form, and the comment must be in the closure BEFORE the
SQL, like this:

sql {
comment('we should not have deleted this...')
'delete from my_table'
}

The stop change can take a message as an argument as well as an
attribute. In other words, stop 'message' works as well as the more
XMLish stop(message: 'message')

A customPrecondition can take parameters. the XMLish way to pass them
is with param(name: 'myParam', value: 'myValue') statements in the
customPrecondition's closure. In the Groovy DSL, you can also have
myParam('myValue')
* The validChecksum element of a change set is not well documented.
Basically you can use this when changeSet's current checksum will not match
what is stored in the database. This might happen if you, for example want to
reformat a changeSet to add white space. This doesn't change the
functionality of the changeset, but it will cause Liquibase to generate new
checksums for it. The validateChecksum element tells Liquibase to
consider the checksums in the validChecksum element to be valid, even
if it doesn't match what is in the database.
* The Liquibase documentation tells you how to set a property for a
databaseChangeLog by using the property element. What it doesn't tell
you is that you can also set properties by loading a property file. To do
this, you can have property(file: 'my_file.properties') in the closure
for the databaseChangeLog.
* Liquibase has an includeAll element in the databaseChangeLog that
includes all the files in the given directory. The Groovy DSL implementation
only includes groovy files, and it makes sure they are included in
alphabetical order. This is really handy for keeping changes in a different
file for each release. As long as the file names are named with the release
numbers in mind, Liquibase will apply changes in the correct order.
* Remember, the Groovy DSL is basically just Groovy closures, so you can use
groovy code to do things you could never do in XML, such as this:

Items that were left out of the XML documentation

The createIndex and dropIndex changes have an undocumented
associatedWith attribute. From an old Liquibase forum, it appears to be
an attempt to solve the problem that occurs because some databases
automatically create indexes on primary keys and foreign keys, and others
don't. The idea is that you would have a change to create the primary key or
foreign key, and another to create the index for it. The index change would
use the associatedWith attribute to let Liquibase know that this index
will already exist for some databases so that Liquibase can skip the change
if we are in one of those databases. The Liquibase authors do say it is
experimental, so use at your own risk...

The executeCommand change has an undocumented os attribute. The
os attribute is a string with a list of operating systems under which
the command should execute. If present, the os.name system property
will be checked against this list, and the command will only run if the
operating system is in the list.

The column element has some undocumented attributes that are pretty
significant. They include:

valueSequenceNext, valueSequenceCurrent, and
defaultValueSequenceNext, which appear to link values for a column
to database sequences.

A column can be set auto-number if it the autoIncrement attribute is
set to true, but did you know that you can also control the starting
number and the increment interval with the startWith and
incrementBy attributes?

The constraints elementt also has some hidden gems:

Some databases automatically create indexes for primary keys. The
primaryKeyTablespace can be used to control the tablespace.

A foreign key can be made by using the references attribute like
this: references: 'monkey(id)', It can also be done like this:
referencedTableName: 'monkey', referencedColumnNames: 'id' for those
who prefer to separate out the table from the column.

There is also a checkConstraint attribute, that appears to be
useful for defining a check constraint, but I could not determine the
proper syntax for it yet. For now, it may be best to stick to custom
sql changes to define check constraints.

The documentation for version 3.1.1 of Liquibase mentions the new
beforeColumn, afterColumn, and position attributes that you
can put on a column statement to control where a new column is placed in
an existing table. What the documentation leaves out is that these attributes
don't work :-)

License

This code is released under the Apache Public License 2.0, just like Liquibase 2.0.

TODOs

Support for the customChange. Using groovy code, liquibase changes and database SQL in a changeSet.

Support for extensions. modifyColumn is probably a good place to start.